This invention relates generally to the field of modular card shelf systems, and more particularly, to a method and system for controlling the supply of power to a circuit card in a card shelf.
Telecommunications systems are generally configured as modular card shelf assemblies to optimize space efficiency within a central office or other similar facilities. Card shelves include discrete circuit cards having different functions that communicate with each other and that receive power across a backplane. The circuit cards each individually plug in to the backplane, that allows any card to be easily replaced in the event of failure.
In many applications, some or all of the circuit cards must be hot-swappable in that they can be inserted and extracted from the card shelf while the card shelf is completely powered up and operational. Because the power supply is active during hot-swapping operations, circuit cards being inserted and extracted from the card shelf often arc to the backplane across the power connection pins during insertion and extraction.
A traditional technique to solve the arcing problem during hot-swapping operations is to use filtering capacitors on the power connection pins to protect the circuitry. The use of capacitors, however, adds expense to the system, is not reliable, and can affect operational signal characteristics. Another traditional technique to counter arcing is to use connection pins of different lengths in order to control the order at which circuits on the card being swapped are connected to or disconnected from the backplane. This approach requires careful analysis of the order to power up the circuits, is unreliable and involves some amount of arcing.
The present invention provides a method and system for controlling the supply of power to circuit cards in a card shelf that substantially eliminate or reduce the problems and disadvantages associated with previous systems and methods. In particular, the supply of power to power connectors on the backplane for a card is individually controlled to allow the card to be connected to or disconnected from the backplane while power to the connectors, and thus the card, is shut off.
In accordance with one embodiment of the present invention, a method and system for controlling the supply of power to a circuit card in a card shelf includes automatically generating a deactivation signal in response to disconnection of a non-power link between the circuit card and a backplane of the card shelf. Power is automatically removed from a power link between the circuit card and the backplane while the power link is connected in response to the deactivation signal.
More specifically, in accordance with a particular embodiment of the present invention, the deactivation signal is automatically generated in response to disconnection of a non-power link between the circuit card and the backplane. The non-power link is configured to disconnect prior to disconnection of the power link. The non-power link may include a pin that is shorter than a power pin of the power link.
In accordance with another aspect of the present invention, an activation signal is automatically generated in response to connection of the non-power link between the circuit card and the backplane of the card shelf. The supply of power is automatically restored to the power link between the circuit card and the backplane in response to the activation signal. The activation signal and the deactivation signal may be disparate values of a common signal. In this and other embodiments, the supply of power to the power link is controlled at the power supply.
Technical advantages of the present invention include providing an improved card shelf for a telecommunications node. In particular, the card shelf automatically controls the supply of power to circuit cards to allow the cards to be hot-swapped without arcing. Accordingly, the cards can be safely inserted and/or removed during operation of the node.
Another technical advantage of the present invention includes providing an improved method and system for inserting and extracting circuit cards in an operational card shelf. In particular, the supply of power to power connectors for a card is automatically shut off when the card is disconnected from the backplane. The supply of power to the power connectors is automatically resumed after a replacement card has been connected to the backplane. Accordingly, arcing between the card and the backplane is eliminated during insertion and extraction operations.
Still another technical advantage of the present invention includes providing a method and system for controlling the supply of power to card slots at the power supply. In particular, the supply of power is controlled at the power supply to remove power from backplane connections for a card slot during hot-swapping operations. By controlling the supply of power to the cards at an off-card location, space is saved on the card and additional features may be added.
Yet another technical advantage of the present invention includes providing an improved method and system for providing power to circuit cards during hot swap operations. During card extraction, power is immediately shut off prior to disconnection of the circuit card. During card connection operations, power is ramped up only after connection of the card to the backplane. Thus, circuit powering is completely controlled during card hot-swapping.